Arnoux's beaked whale is poorly known and closely resembles the northern Baird's beaked whale (although they live in different hemispheres). They grow up to 9.75 metres long.

Appearance:

The Arnoux's beaked whale has a pronounced dolphin-like beak which, unusually, has two sets of front teeth in the front of the lower jaw. In both the male and the female, the front pair are visible when the mouth is closed. Its head is small and steep with a bulbous melon. An Arnoux's beaked whale body is dark and spindle-shaped and covered in white scratches and scars, suggesting male-male fighting. At times they may appear brown or even orange due to microscopic algae called diatoms covering the body. The Arnoux's beaked whale has small flippers which have rounded tips and the dorsal fin is small, slightly hooked and situated well back on the body.

Behaviour:

The Arnoux's beaked whale may show its flukes before a deep dive and it can remain underwater for up to an hour. The blow is low and bushy. Single animals have been recorded at sea, but Arnoux's beaked whales are more commonly found in groups of about 6 to 10 animals. Occasionally, they have been seen in much bigger groups of up to 80. They tend to avoid people and swim slowly when at the surface.

Distribution:

Arnoux's beaked whales are found only in the southern hemisphere. They have been recorded as far south as the Ross Sea and there may be some seasonal movement from deep Antarctic waters to continental shelf areas. The majority of strandings have been around New Zealand and most of the sightings data is from the Tasman Sea and near Albatross Cordillera in the South Pacific. Arnoux's beaked whales tend to be seen in areas of deep water such as escarpments, seamounts and other areas with steep-bottomed slopes. They seem to be well adapted to life in ice-covered waters and are known to enter regions where there is pack ice, living close to the ice edge during the summer. Climate change may be a threat to the species. Arnoux's beaked whales' worldwide population is unknown. There has been no substantial commercial hunting, though some have been taken for scientific study. They are listed by IUCN as Data Deficient.